Abstract: Provided is a pretreatment method for directly seeding an in vitro microtuber in an open field including: sterilizing a washed in vitro microtuber with chlorine dioxide and drying the sterilized in vitro microtuber; irradiating the dried in vitro microtuber with light and greening the dried in vitro microtuber; putting the greened in vitro microtuber in a storage container and storing the greened in vitro microtuber in a temperature range of 2 to 4° C.; and germinating the in vitro microtuber. The in vitro microtuber can quickly adapt to environment when directly seeded on a field, an early-stage management of the in vitro microtuber is facilitated, and physiological functions thereof such as vitamin synthesis is activated.